Our research program on transmissible and genetic neurodegenerative diseases rests upon the Animal Core. The need for propagation of prions to high titers and for bioassay of prion infectivity requires extremely large numbers of mice and hamsters. Without proper animal facilities, personnel and support, the studies described to date could not have been performed, and the studies outlined in this proposal cannot be carried out. Over the past fifteen years we have accumulated a large amount of experience with hamsters and mice infected with scrapie prions. This experience has helped us to delineate the minimum requirements for operating a successful facility. We have a well-trained staff of animal caretakers directed by skilled supervisors and a veterinarian. Many steps are involved in the care of animals inoculated with prions. The inoculations must be done with the greatest of skill. The animals must be given exquisite animal care and then they must be checked with great frequency and the diagnosis of scrapie made with extreme reliability. Careful records must be kept and selected animals must be examined for neuropathologic evidence of scrapie. With the recent development of transgenic mice expressing foreign PrP genes, the number of animals and the complexity of the record keeping in the animal core will increase since each new transgenic line represents a new strain of mouse. We are very fortunate to have a very skilled veterinarian, Dr. Marilyn Torchia, directing the animal facility operation and to have the University of California facilities available to us at Hunters Point in San Francisco. The details of the animal care program are described in Core A, as well as the animal usage for each scientific project.